<!--
 * @Author: YZH_skr 1941972061@qq.com
 * @Date: 2023-04-08 19:45:58
 * @LastEditors: YZH_skr 1941972061@qq.com
 * @LastEditTime: 2023-04-08 19:49:57
 * @FilePath: \code\JS20230408.html
 * @Description: 这是默认设置,请设置`customMade`, 打开koroFileHeader查看配置 进行设置: https://github.com/OBKoro1/koro1FileHeader/wiki/%E9%85%8D%E7%BD%AE
-->
<script>
    var a = 123;
    console.log(typeof(a));
    a = a.toString();
    console.log(typeof(a));

    var a = 123;
    a = String(a);
    console.log(a);
    console.log(typeof a);

    var b = undefined;
    b = String(b);
    console.log(b);
    console.log(typeof b);

    var c = null;
    c = String(c);
    console.log(c);
    console.log(typeof c);

</script>